Millimeters of Mercury to Standard Atmospheres Converter
1 millimeter of mercury ≈ 0.00131578979 standard atmospheres
Almost identical to the torr, but defined separately. This uses conventional mmHg, not a temperature-specific mercury-column realization.
1 millimeter of mercury equals 0.00131579 standard atmospheres
How to convert millimeters of mercury to standard atmospheres
Unit conversion preserves the pressure reference. Gauge pressure and absolute pressure are different readings; changing between them also needs the ambient pressure. Mercury and water-column units use the conventions stated in their unit notes.
atm = mmHg × 0.001315789785One millimeter of mercury is 0.001315789785 standard atmospheres, so a single multiplication converts any value.
0.0131579 atm ≈ 10 × 0.001315789785Almost identical to the torr, but defined separately. This uses conventional mmHg, not a temperature-specific mercury-column realization.
Millimeters of mercury to standard atmospheres conversion table
Common values in millimeters of mercury, converted to standard atmospheres.
| Millimeters of mercury (mmHg) | Standard atmospheres (atm) |
|---|---|
| 1 | 0.0013157898 |
| 2 | 0.0026315796 |
| 3 | 0.0039473694 |
| 4 | 0.0052631591 |
| 5 | 0.0065789489 |
| 10 | 0.013157898 |
| 20 | 0.026315796 |
| 25 | 0.032894745 |
| 50 | 0.065789489 |
| 100 | 0.13157898 |
| 250 | 0.32894745 |
| 500 | 0.65789489 |
| 1,000 | 1.3157898 |
About these units
millimeter of mercurymmHg
The conventional millimetre of mercury: 133.3224 Pa, following the NIST SP 811 convention.
Reference: NIST Special Publication 811.
standard atmosphereatm
Exactly 101,325 pascals, the defined standard sea-level pressure.
Reference: CGPM 1954.
Sources and precision
Table results are rounded to 8 significant digits; formula constants may be rounded to 10. Worked example answers use 6 significant digits. The converter starts at 6 significant digits and lets you change display precision. Calculations use the stored factors without intermediate rounding. Exact unit definitions do not make an input measurement more precise; conventional and measured factors follow the assumptions stated here.